Development of a low-cost, extended-range, autorefractor This project proposal seeks to develop technologies that will lower the cost of and increase the accessibility of refractive eye care, especially in low-resoure settings. We propose to advance our previously developed low-cost, handheld device capable of automatically measuring the optical properties of the eye based on the technique of wavefront aberrometry. The proposed work will specifically focus on the development of optical and software systems will extend the device's measurement range to work on a larger range of refractive errors. First, optical systems with no moving parts will be developed which enable the device to work on subjects with severe myopia or hyperopia (<--6 diopters or >6 diopters of refractive error). Second, algorithms that make the device easy and intuitive to use will be implemented. Third, a handheld prototype incorporating these improvements will be constructed and validated in model eye systems. The output of this project will be a functional, extended-range prototype that will facilitate the fild-testing and commercialization of a low-cost, easy-to-use device to dispense eyeglass prescriptions.